Do marshmallows make your tongue swell? Gummy bears make you itchy? If you've answered yes and are allergic to gelatin, you will want to take some precautions when getting the flu shot. While the vaccine is recommended for those six months of age and older, a case report being presented at the American College of Allergy, Asthma and Immunology (ACAAI) Annual Scientific Meeting notes that individuals with a gelatin allergy can have a mild to severe reaction from the shot.

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"Gelatin is used in the flu shot, as well as other vaccines, as a stabilizer," said Stephanie Albin, MD, an allergist and ACAAI member. "Because it is found in the vaccine, those with a known allergy to gelatin can experience allergic reactions, such as hives, sneezing and difficulty breathing."

There is a misconception about allergies and the flu shot, with many believing those with an egg allergy should not receive the vaccination. But last month, ACAAI published an update that found even those with a severe egg allergy can receive the vaccine without special precautions.

"Gelatin reactions can cause hives, swelling, itchiness, shortness of breath and a severe life-threatening reaction known as anaphylaxis," explained Dr. Albin. "Because of this, precautions should be taken, such as having a board-certified allergist administer the vaccine in a person with known gelatin allergy in case a reaction occurs."

Gelatin can contain proteins derived from cow, pig or fish. Gelatin can be found in a variety of foods and pharmaceuticals, including gummy vitamins, marshmallows and candy.

"Gelatin allergy is very rare," said allergist Richard Weber, M.D., ACAAI president. "Many food intolerances can be mistaken as allergies. Those who believe they might have an allergy should be tested and diagnosed by an allergist before taking extreme avoidance measures or skipping vaccinations. The flu shot is an important vaccine and can even be life-saving for individuals that are at an increased risk for severe side effects associated with the flu."